elterich



(No Model.) 2 SheetP-Sheet 1.

0. ELTERIOH. THREAD OUTTING IMPLEMENT.

No. 574,721. H Patented Jan. 5, 1897.

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VVFTNESSES: INVENTOR:

ATTOHN UNITED STATES PATENT OFFICE.

CHARLES ELTERICH, OF NEIV YORK, N. Y.

TH READ-CUTTING IM PLEMENT.

SPECIFICATION forming part of Letters Patent No. 574,721, dated January 5, 1897. Application filed January 14, 1896. Serial No. 575,441. (No mod l.) 7

To all whom it may concern.-

Be it known that 1, CHARLES ELTERICH, a citizen of the United States of America,and a resident of New York, in the county and State of New York, have invented certain new and useful Improvements in ThreadCutting Implements, of which the following is a specification.

My invention has reference to improvements in thread-cutting dies; and it has for its object to provide an implement of this character adapted for the purpose of cutting a perfect continuous thread and one which can be used for a long time without appre- I 5 ciable Wear. To this end I construct the implement with a cutting-thread of substantially constant diameter at its bottom, the top of the thread being cut away at the entering end and gradually increased by steps of one or more substantially flat-top teethtoward the finishing end.

The nature of my invention will best be understood when described in connection with the accompanying drawings, in which- 2 5 Figure 1 represents a vertical section, on

an enlarged scale, of a die embodying myinvention. Fig. 2 is a bottom view, part being broken away. Fig. 3 is a diagrammatic view illustrating the construction of the cutting- 0 thread. Figs. 4:, 5, and 6 are detail views illustrating the manner of constructing clearance for the cutting-thread. Fig. 7 is a central cross-section showing the shape of the orifice in the die before forming the thread.

5 Similar letters and numerals ,of reference stepped. The portion of the thread between the lines 5 5 and 6 Grepresents the finishing 5o portion of the die, and. in this portion the thread is of the full standard size. The portion of the thread between thelines 7 7 and This hole is fore consists of a series of gradually-increasing portions 6, f, and g, composed of one or more substantially flat-top teeth, so that the material acted upon is gradually cut away up to the finishing portion g, while the successive portions always out outwardly from the baseline of the thread. If desired, intermediate taper portions, as e f, as indicated by dotted lines in Fig. 3, may be introduced to facilitate the cutting.

In practice I'remove a portion of the die at the entering end of the same, as shown in Figs. 1 and 2, to facilitate entering, while'a likeremoval may be madeat the finishing end to enable the die to be reversed for the usual purpose. To provide for clearance, I

first back oit the teeth, as at j, with a suitable cutter, as shown in Figs. 4 and 5, and

then file down the portion l to obtain the shape shown in Fig.- 6. I The die is finished in the usual manner.

With the present construction of die I obtain a perfect thread, which is'smooth and solid and is not expanded or stretched bodily. The thread not being stretched by the die, it possesses the full strength of the material. All the known dies produce more or less stretching of the threads, and the pitch is thereby increased from the standard. Furthermore, in my present construction the diameter of the shank at the terminal threads is gradually increased, thereby producing bolts of extraordinary strength at the usual weakpoint. v f

The cutting action of a die embodying my invention may be described as quite similar to the action of the thread-cuttingtool in a lathe in making'a succession of cuts.

\Vhile I have herein 'statedthat the baseline of the threads must be substantially uniform in diameter I do not wish to be understood that the said base-line cannot be slightly taper.

It is of course to be understood that in adapting the invention to dies for cutting threads on pipes, where a taper-thread is usually formed, the baseline of the thread must have a constant taper corresponding to that of the stepped cutting-line.

hat I claim as new is 1. A die whose cutters are formed from a thread, the base-line of which is substantially straight from bottom to top of said die; the top of the thread being cut away at the entering end and gradually increased by steps consisting of one or more substantially flattop teeth to the finishing end, substantially as described.

2. A die Whose cutters are formed from a thread, the base-line of whichis substantially straight from bottom to top of said die; said thread having its top cut away at its entering end, but having its full width at the baseline, and said thread being gradually increased toward its apex by steps consisting of one or more substantially flat-top teeth, substantially as described. I

A die whose cutters are formed from a thread, the base-line of which is substantially straight from bottom to top of said die, and having its top cut away at the entering end and gradually increased by steps of one or more substantially flat-top teeth; the backs of said teeth being cleared circumferentially backward and tapered from the clearance portion to the cutting edge, substantially as described. v

4. A die provided with a cutting-thread of constant taper at its base-line; the top of the thread being cut away at the entering end and gradually increased by steps consisting of one or more substantially flat-top teeth to the finishing end, substantially as described.

111 testimony that I claim the foregoing as my invention 1 have signed my name, in presence of two witnesses, this Zith day of December 1895.

CHAS. ELTERICH. lVitnesses:

A. FABER DU FAUR, J12, G. W. EISENBRAUN. 

